Nickel(II)-Catalyzed Synthesis of Sulfinates from Aryl and Heteroaryl Boronic Acids and the Sulfur Dioxide Surrogate DABSO

We report a redox-neutral Ni(II)-catalyzed sulfination of readily available aryl and heteroaryl boronic acids. Using the combination of commercially available, airstable NiBr2 center dot(glyme), a commercially available phenanthroline ligand, and DABSO, boronic acids are efficiently converted to the corresponding sulfinate salts, which can be further elaborated to valuable sulfonyl-containing groups, including sulfones, sulfonamides, sulfonyl fluorides, and sulfonate esters. The catalyst loading can be reduced to 2.5 mol % on a gram scale. This practically simple protocol tolerates an unprecedented range of pharmaceutically relevant and electron-poor (hetero)aryl boronic acids, allowing the direct synthesis of active pharmaceutical ingredients.